High-speed data communication is conducted between a transmitter (TX) and a receiver (RX) over a differential channel. A finite impulse response (FIR) filter in the TX is used to equalize the signal transmitted over the differential channel such that the signal can be interpreted correctly upon receipt at the RX. Use of the FIR filter in the TX is particularly important for serializer/deserializer (SERDES) input/output (IO) communications. The effect of the FIR filter on the signal is defined by a setting of various function parameters in the FIR filter. Appropriate settings for the various function parameters in the FIR filter are dependent upon the differential channel properties. Because the properties of the differential channel can be influenced by external factors, such as environmental factors like temperature and humidity, pre-determined values for the various function parameters in the FIR filter may become invalid during operation of the differential channel for high-speed data communication.
For example, at low data rates (e.g., 2.5 Gbps to 3.125 Gbps), the TX FIR filter settings can be set in advance, and there will likely be no need to change the TX FIR filter settings during system operation. However, as the data rate increases (e.g., beyond 3.125 Gbps), the variation of differential channel loss as a function of temperature and humidity becomes sufficiently large that the pre-set TX FIR filter settings will likely become invalid, thereby requiring adjustment of the TX FIR filter settings during system operation. In high-speed data communications (e.g., exceeding 3.125 Gbps), real-time continuous optimization of the TX FIR filter settings is preferred to maintain adequate equalization of the TX output signal in the presence of variations in temperature and humidity.
While it is possible to theoretically estimate the required FIR filter settings based on a known pulse response of the end-to-end channel, there is no existing way to capture the pulse response of the end-to-end channel in real-time during an actual high-speed communication process, particularly a communication process utilizing a non-analog-to-digital converter (non-ADC)-based RX. Therefore, existing technologies do not enable real-time continuous optimization of TX FIR filter settings, as required to maintain adequate equalization of the TX output signal in the presence of variations in temperature and humidity.